WASHINGTON - New York's two Democratic senators recently joined a small group of federal elected officials who have released their tax returns.

Their disclosures come as pressure builds on Republican presidential candidate Mitt Romney to release more of his returns.

Within the same 24-hour period, Chuck Schumer and Kirsten Gillibrand became the first Senate lawmakers to post their income tax returns on their official government websites.

Schumer released his 2011 tax return, while Gillibrand released five years of returns dating to 2007, when she began her congressional tenure as a member of the House.

"The more I kept reading in the press about this debate about presidential taxes, the more I really thought it was the right thing to do,'' Gillibrand said in an interview. "I thought it was an additional step I could take to lead by example.''

Gillibrand considers her decision a natural next step in her efforts to make government more transparent. During her first year in the House, she created a "Sunlight Report'' on her official website. The report made her the first member of Congress to post all her requests for earmarked spending, her schedule and her annual personal financial disclosure report.

Earlier this year, Gillibrand was a leading Senate advocate for passage of the STOCK Act, which requires members of Congress, top administration officials and federal judges to publicly report most financial transactions of $1,000 or more within 45 days.

The legislation, first proposed in 2006 by Democratic Rep. Louise Slaughter of New York, gained momentum this year as lawmakers focused on restoring public confidence in Congress.

Schumer, now the No. 3 Senate Democratic leader, said he decided on his own to release his tax returns and discussed the issue with his staffers.

"When it became an issue with Gov. Romney, we said, why don't we do it?'' Schumer said. "We should do it. It's the right thing to do. And so, we are doing it.''

Two other Senate Democrats - Richard Durbin of Illinois and Herb Kohl of Wisconsin - have been releasing their annual tax returns since the 1980s.

Durbin, the Senate majority whip, began releasing his returns in 1982, when he was first elected to the House, according to spokesman Max Gleischman.

"He attaches them to his annual financial disclosure,'' Gleischman said. "That is a publicly available document and easily available.''

Kohl, who is one of the wealthiest members of the Senate and owns the Milwaukee Bucks professional basketball team, released his returns for 1984 through 1987 during his first Senate campaign in 1988, according to spokeswoman Lynn Becker. Kohl has released his annual tax returns every year since then, sending copies to members of the media who request them.

Reporters covering Washington for newspapers owned by McClatchy recently spent three months trying to obtain tax returns from all 100 members of the Senate and all 435 House members. But only 17 either released their returns or provided similar data, according to a July 18 McClatchy story.

Schumer and Gillibrand did not respond to the request from McClatchy. They said the request didn't influence their ultimate decision to release their returns.

Schumer posted his 2011 income tax return on his Senate website on July 26. Gillibrand posted her returns for 2007 through 2011 a day later.

Craig Holman, government affairs lobbyist for Public Citizen, said the McClatchy survey shows "how infrequent and uncommon it is for members of Congress to release their tax returns. There hasn't been generally been an expectation that they do so.''

The annual personal financial disclosures members of Congress are required to file list their assets, investment income and liabilities in broad ranges - such as $100,000 to $1 million - up to $5 million. This year, for the first time, lawmakers were also required to also list any mortgages they owed.

Kathy Kiely, managing editor for the Sunlight Reporting Group, said the reports don't provide a full picture of a lawmaker's finances.

"The more we can know about where the pressure points on lawmakers are, the more we can be sure the decisions they make are in the interest of the general public rather than some private gain,'' Kiely said.

Some lawmakers voluntarily provide additional information.

Schumer's personal financial disclosure forms list the salary earned by his wife, Iris Weinshall, a senior administrator at the City University of New York. Her salary also is publicly available on the university's website.

Schumer said there was no significant reason not to release his own tax return.

The couple's 2011 federal return shows they reported a combined adjusted gross income of $371,294. They owed $92,407 in taxes - including $13,156 in Alternative Minimum Tax - on a taxable income of $302,821. They received a refund of $4,408 because they had $96,815 in withholding.

Gillibrand released several years of her tax returns in February 2009, shortly after she was appointed to the Senate by Gov. David Patterson to fill the vacancy left by the resignation of Secretary of State Hillary Rodham Clinton. She let reporters view copies of returns dating to 2005 at a downtown Washington law office, but the reporters were prohibited from copying them.

Her 2005 return showed Gillibrand earned $509,269 that year while working as an attorney at the prominent Manhattan law firm of Boies, Schiller and Flexner. Gillibrand and her husband, Jonathan, a stock day trader, together grossed $533,852 and paid $147,257 in federal taxes, including $4,621 in Alternative Minimum Tax.

Since 2006, when Gillibrand quit her legal career to run for the House, her income has dropped. For four of the past five years, she and her husband reported an adjusted gross income of under $200,000.

The one exception was 2008, when their adjusted gross income rose to $397,792, boosted by $197,920 in capital gains from Jonathan Gillibrand's day trading. During the onset of the housing meltdown, he made short-term gains by trading in firms such as KB Homes, Meritage Homes Corp, homebuilder Ryland Group, Home Depot, Deckers Outdoor Corp. and Research in Motion, the maker of BlackBerry smart phones. That year the couple paid $103,900 in federal taxes.

For calendar year 2011, the Gillibrands reported an adjustable income of $165,614 and paid $28,828 in taxes.

Gillibrand said her decision to released her more recent tax returns were not influenced by her re-election campaign against Republican Wendy Long.

Long plans on releasing her 2011 tax return and is calling on Gillibrand to post online her return for 2006, the year she first campaigned for Congress, according to Long's spokesman, David Catalfamo.